“Black Lives Matter” is painted repeatedly on the exterior wall behind the N’Namdi Center for Contemporary Art, Friday, Sept. 18, 2015. in Detroit. Renda Writer, a white muralist from Miami, is expressing his support for the “Black Lives Matter” movement ... more >

DETROIT (AP) - A white muralist from Miami is expressing his support for the “Black Lives Matter” movement one word at a time outside of a Detroit art gallery.

When the commissioned project on the wall behind the N’Namdi Center for Contemporary Art is completed, Renda Writer estimates he will have scrawled the slogan thousands of times - in white paint and white market on black cinderblock walls.

I believe all lives matter,” he told The Associated Press on Friday from the top rungs of a ladder, but added, “it is black people being killed in disproportionate numbers unjustly by law enforcement without due process.”

The slogan surfaced after the 2012 slaying of 17-year-old Trayvon Martin in Florida, but became a well-known movement following last summer’s fatal shooting of 18-year-old Michael Brown by a white police officer in Ferguson, Missouri, and this spring’s death of 25-year-old Freddie Gray while in Baltimore police custody.

Activists have marched under “Black Lives Matter” banners in cities across the country, including protests in Detroit this summer over the fatal shooting of a man by an Immigration and Customs Enforcement agent carrying out an arrest warrant. A prosecutor later deemed the shooting was in self-defense. Some law enforcement agency leaders have said the movement instigates violence against police.

Writer, 37, declined to say how much he is getting paid by the gallery to do the mural. He started Monday and expected to complete it by Saturday.

George N’Namdi also wouldn’t say how much he was paying for the mural, which he said also reflects poverty, unemployment and other societal problems facing blacks.

“Things are happening nationally, and I think it’s good to kind of acknowledge some of the things happening,” N’Namdi said. “Sometimes awareness helps everybody.”

The gallery is in the city’s Midtown neighborhood, walking distance from the Detroit Medical Center, Wayne State University and small eateries.

Clifford Stanley, 69, took a moment to consider the mural as he headed to a doctor’s appointment.

“This is positive,” said Stanley, who is black. “Black lives matter. As a matter of fact, we all as human beings matter.”